Open AccessOn the decomposition of ammonia by high-speed electrons
Publication year - 1928
Publication title -
proceedings of the royal society of london. series a, containing papers of a mathematical and physical character
Language(s) - English
Resource type - Journals
eISSN - 2053-9150
pISSN - 0950-1207
DOI - 10.1098/rspa.1928.0149
Subject(s) - ammonia , decomposition , thermodynamic equilibrium , chemistry , atmospheric pressure , electron , chemical equilibrium , thermodynamics , physics , organic chemistry , meteorology , quantum mechanics
During recent years a knowledge of the ammonia equilibrium has attained a great technical importance. The fact that ammonia decomposes under the action of an electric spark or on passing through a red-hot tube was known as long ago as in the time of Priestly. It was, at this time, regarded as a complete decomposition. The first indication of a certain quantity of the ammonia remaining undecomposed, and thus of the balanced nature of the action, was obtained by Deville in 1805. Measurements on the variation of the equilibrium with temperature, at atmospheric pressure, were made by Haber and Oordt. They found that at 1020°C. the equilibrium mixture contained only 0·012 per cent, by volume of ammonia, whilst at 27°C. the concentration of ammonia was 98·51 per cent. However, at this low temperature the speed of attaining the equilibrium was very slow. Many investigations have been carried out by various methods and different results obtained. The photo- chemical decomposition was investigated by Kuhn, who reported that the decomposition was complete. The equilibrium under the action of α-rays has been studied by Lind and Bardwell, and these authors concluded that equilibrium would be established when 83·3 per cent, of the ammonia was decomposed. Decomposition by means of the silent electric discharge was studied by Le Blane and Davies, who found that the equilibrium was not governed by the ordinary laws of mass action. Experiments with low-voltage electrons have been carried out by Anderson, and by Caress and Rideal. In these experiments, however, the gases where in contact with the glowing filament, which produced the electrons, and thus thermal effects, as instanced by the work of Schwab, Hinshelwood and Burk, might be present. It seemed, therefore, of interest to investigate the decomposition of ammonia by means of electron bombardment under such conditions that the thermal effects where eliminated, and a possibility of attaining this was offered by the use of the new Coolidge cathode-ray tube.